Impact Attenuating Media

ABSTRACT

An impact attenuating device (100) that may be employed to catch falling objects, such as drill pipe, that are suspended in or above the mousehole (90) in a drilling floor includes an elongate housing (200) with first and second ends, an internal chamber, and a housing base spaced-apart from the first housing end. An attenuator base (130) is included in the housing, spaced-apart from the first housing end. At least one stack (160) of impact attenuating media is positioned in the chamber between the first housing end and the attenuator base (130), the stack (160) comprising a plurality of resilient members (162).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 62/222,535 filed Sep. 23, 2015, and entitled “ImpactAttenuating Media,” which is hereby incorporated herein by reference inits entirety for all purposes.

BACKGROUND Field of the Disclosure

This disclosure relates generally to safety devices for handling pipingand other tubulars during drilling operations. More particularly, itrelates to apparatus and systems for capturing piping, other tubulars,and other equipment that can fit inside a borehole and that may beaccidentally dropped while being repositioned on an oil platform orother drilling rig.

Background to the Disclosure

Work around off-shore oil platforms, including drilling and productionequipment, involves lifting, assembling, and dissembling heavy stringsof tubular members, e.g. multiple sections of individual pipes, whichmay be called pipe joints, and other objects connectable to the drillpipe, such as drill bits. During this work, various strings and pipesections must be grasped, transported to a new location and thenrotated, released, and re-grasped. Often times this work is done over ahole in the drilling floor, commonly called a mouse hole, which includesthe hole/opening and a staging or storage area below the opening. Amouse hole is configured to receive one or more pipe joints so thatmultiple pipe joints can be connected together end-to-end before beingmoved as a unit and placed in the well bore. There is a risk thatstrings and pipe sections may be accidentally dropped while beinghandled above or within the mouse hole. A dropped stand of pipe has thepotential of falling to the sea floor below the rig and causing severedamage to the well-head, pipelines or other equipment that is positionedbelow. Such a fall has potential to injure rig personnel and also tocause environmental and economic damage. Equipment and methods formitigating the effect of a falling tubulars on a drilling system wouldbe beneficial to the industry.

BRIEF SUMMARY OF THE DISCLOSURE

These and other needs in the art are addressed in one embodiment by animpact attenuating device. In an embodiment, the device includes anelongate housing comprising first and second housing ends, an internalchamber, and a housing base spaced-apart from the first housing end. Inaddition, the device includes an attenuator base disposed in the housingand spaced-apart from the first housing end. Further, the deviceincludes a first stack of impact attenuating media disposed in thechamber at a location between the first housing end and the attenuatorbase, the stack comprising a plurality of resilient members.

In another embodiment, a drilling apparatus includes a drilling floorwith a mousehole. In addition, the apparatus includes an elongatehousing supported in a position below the drilling floor and comprisingan internal chamber positioned beneath the mouse hole. Further, theapparatus includes at least a first impact attenuating stack disposed inthe chamber and comprising a plurality of resilient members disposedalong an elongate guide member. The resilient members include analignment aperture that receives the guide member therethrough.

In another embodiment, an impact attenuating device comprises alongitudinal axis and an elongate housing. The housing includes firstand second housing ends spaced-apart along the axis, an internalchamber, and a housing base axially spaced from the first housing end.In addition, the device includes an impact attenuating media assembly inthe housing. The media assembly includes: a receiver; an attenuator baseaxially spaced-apart from the receiver and having an alignment hole; atleast a first stack of impact attenuating media disposed between thereceiver and the attenuator base, the stack comprising a plurality ofresilient members; and a guide member extending from the receiver to theattenuator base, through the stack.

Thus, embodiments described herein include a combination of features andcharacteristics intended to address various shortcomings associated withcertain prior devices, systems, and methods. The various features andcharacteristics described above, as well as others, will be readilyapparent to those of ordinary skill in the art upon reading thefollowing detailed description, and by referring to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the disclosed embodiments, reference willnow be made to the accompanying drawings:

FIG. 1 shows a perspective front view of an embodiment of an off-shoredrilling system including an impact attenuating device in accordancewith principles described herein, the impact attenuating devicecomprising an impact attenuating media assembly with three guide rods;

FIG. 2 shows a close-up side view of the impact attenuating device ofFIG. 1 along a cross-section 2-2, having an impact attenuating mediaassembly installed in a housing;

FIG. 3 shows an upper end view of the impact attenuating device of FIG.2;

FIG. 4 shows a lower end view of the impact attenuating device of FIG.2;

FIG. 5 shows an end view of the base of the impact attenuating mediaassembly of FIG. 2;

FIG. 6A shows an end view of a resilient member (a “donut”) of theimpact attenuating media assembly within FIG. 2;

FIG. 6B shows a side view of the resilient member within FIG. 6A alongthe section 6B-6B;

FIG. 7 shows an end view and a cross-sectional side view of a spacer ofthe impact attenuating media assembly within FIG. 2; the spacerconfigured to couple three resilient members on each side and to receivethree guide rods;

FIG. 8 shows an end view of the housing base of the impact attenuatingdevice of FIG. 2;

FIG. 9 shows cross-sectional side view of the impact attenuating mediaassembly of the device of FIG. 2 as it may be arranged duringmake-up/assembly;

FIG. 10 shows a full side view, in cross-section, of the impactattenuating device of FIG. 2 having the impact attenuating mediaassembly installed in the housing;

FIG. 11 shows a cross-sectional view of the impact attenuating device ofFIG. 10 with the impact attenuating media assembly fully-compressedunder load;

FIG. 12 shows an end view and a cross-sectional view side view ofanother spacer that may be used to form the impact attenuating mediaassembly of FIG. 9 in accordance with principles described herein; thespacer is configured to couple one resilient member on each side and toreceive one guide rod;

FIG. 13 shows an upper end view and a lower end view of another impactattenuating device compatible with the impact attenuating device of FIG.1 in accordance with principles described herein.

FIG. 14 shows a side view of the impact attenuating device of FIG. 13along a cross-section 14-14;

FIG. 15 shows an end view of a spacer of the impact attenuating mediaassembly of FIG. 14, the spacer configured to couple four resilientmembers on each side and to receive four guide rods;

FIG. 16 shows an end view of another spacer compatible with an impactattenuating media device similar to the devices of FIG. 2 and FIG. 14 inaccordance with principles described herein, the spacer being square andconfigured to couple four resilient members on each side and to receivefour guide rods;

FIG. 17 shows components of an impact attenuating media assembly,including a receiver, a base, and a billow hose in accordance withprinciples described herein;

FIG. 18 shows a side view in cross-section of another impact attenuatingdevice in accordance with principles described herein, the impactattenuating device comprising having an impact attenuating mediaassembly installed in a housing and being compatible with the drillingsystem of FIG. 1;

FIG. 19 shows an isometric, exterior view of the impact attenuatingdevice of FIG. 18;

FIG. 20 shows a close-up view of the end of the impact attenuating mediastack of the impact attenuating device of FIG. 18;

FIG. 21 shows a stabilizer of the impact attenuating device of FIG. 18;

FIG. 22 shows an end view in cross-section of the impact attenuatingdevice of FIG. 18 along a section 22-22;

FIG. 23 shows an end view of an impact attenuating media element of theimpact attenuating device of FIG. 18 and FIG. 22, the media elementhaving a star-shaped hole for receiving a guide member; and

FIG. 24 shows an impact attenuating media element in accordance withprinciples described herein, suitable for use with any of theattenuating devices disclosed herein.

NOTATION AND NOMENCLATURE

The following description is exemplary of certain embodiments of thedisclosure. One of ordinary skill in the art will understand that thefollowing description has broad application, and the discussion of anyembodiment is meant to be exemplary of that embodiment, and is notintended to suggest in any way that the scope of the disclosure,including the claims, is limited to that embodiment.

The drawing figures are not necessarily to scale. Certain features andcomponents disclosed herein may be shown exaggerated in scale or insomewhat schematic form, and some details of conventional elements maynot be shown in the interest of clarity and conciseness. In some of thefigures, in order to improve clarity and conciseness, one or morecomponents or aspects of a component may be omitted or may not havereference numerals identifying the features or components that areidentified elsewhere. In addition, within the specification, includingthe drawings, like or identical reference numerals may be used toidentify common or similar elements.

As used herein, including in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . .” In addition,the term “couple” or “couples” means either an indirect or directconnection. Thus, if a first component couples or is coupled to a secondcomponent, the connection between the components may be through a directengagement of the two components, or through an indirect connection thatis accomplished via other intermediate components, devices and/orconnections. The recitation “based on” means “based at least in parton.” Therefore, if X is based on Y, X may be based on Y and any numberof other factors. The word “or” is used in an inclusive manner. Forexample, “A or B” means any of the following: “A” alone, “B” alone, orboth “A” and “B.”

In addition, the terms “axial” and “axially” generally mean along orparallel to a given axis, while the term “axially aligned” morespecifically means along a given axis. The terms “radial” and “radially”generally mean perpendicular to an axis. For instance, an axial distancerefers to a distance measured along or parallel to a given axis, and aradial distance means a distance measured perpendicular to the axis.

Furthermore, any reference to a relative direction or relative positionis made for purpose of clarity, with examples including “top,” “bottom,”“up,” “upper,” “upward,” “left,” “leftward,” “right,” “right-hand,”“down,” “lower,” “clockwise,” and the like. For example, a relativedirection or a relative position of an object or feature may pertain tothe orientation as shown in a figure or as described. If the object orfeature were viewed from another orientation or were positioneddifferently, it may be appropriate to describe the direction or positionusing an alternate term.

DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS

This disclosure presents embodiments of an apparatus and a relatedsystem for handling strings and individual sections of pipe and othertubulars on or around an oil platform or oil rig, including off-shoreoil systems. The apparatus and a related system include an impactattenuating device for capturing a falling tubular. During impact, thekinetic energy of the falling tubular is converted and stored aspotential energy in multiple resilient members that experiencedisplacement or expansion perpendicular to the direction of impact. Inat least some embodiments, after the captured member is removed, theresilient members recover at least a portion of their original size andshape and at least a portion of their original impact-absorbingcapacity.

Referring now to FIG. 1, an embodiment of an offshore drilling system 10is shown. In this embodiment, drilling system 10 includes a rigstructure 12 having a drilling deck 14 and a mast or derrick 15 coupledto deck 14. Vertically-extending derrick 15 supports a drill string 16suspended within a drilling riser defining a drilling centerline 18. Inparticular, the upper portion of the derrick 15 includes a top drivesystem 25 and pipe elevator 26 that support drill string 16, whichextends through the drilling deck 14, a drilling riser, and into asubsea borehole.

One or more storage areas are provided for individual pipe joints 20 andpipe stands 22. In this embodiment, a first storage unit 21 temporarilystores a plurality of pipe joints 20 in a horizontal orientation on deck14, and a second storage unit 23 temporarily stores a plurality of pipestands 22 in a vertical orientation. Storage unit 23 includes a rackingor finger board 30 extending horizontally from derrick 15 above drillingdeck 14. As shown, storage units 21, 23 are offset or spaced away fromcenterline 18. Pipe joints 20 in storage unit 21 are used to assemblypipe stands 22, which may then be added to drill string 16. In thisembodiment, each pipe stand 22 is made of four individual pipe joints 20connected together end-to-end. In other examples, a pipe stand 22 ismade of more or fewer individual pipe joints 20, such as two or threeindividual pipe joints 20 connected together end-to-end.

Referring still to FIG. 1, an embodiment of a mouse hole 90 is offsetfrom centerline 18, and extends vertically downward from drilling deck14. Mouse hole 90 includes a rotary interface 92 disposed adjacent andcoupled to drilling deck 14 below a hole 17, a plurality of receivingtubes or guide tubes 94, and an impact attenuating device 100, allconnected in series along a vertical, mouse hole axis 95 and extendingbelow drilling deck 14. Mouse hole 90 or portions of it may also becalled a rotary sock. Mouse hole 90 may be used to assemble anddisassemble a plurality of pipe joints 20 into pipe stands 22.

In general, any suitable pipe handling device or system may be used toengage individual pipe joints 20, as well as individual pipe stands 22,to manipulate and move joints 20 and stands 22 between storage units 21,23, mouse hole 90, and centerline 18. The combined operation of the pipehandling system and mouse hole 90 may be by manual or robotic means,which can include automated or remote control. Examples of suitable pipehandling systems are disclosed in U.S. Pat. Nos. 7,841,415; 7,228,919;6,976,540; 7,736,119; 7,083,007; and U.S. Patent Application PublicationNos. 2007/0251728 and 2008/0164064, each of which is hereby incorporatedherein by reference in its entirety for all purposes.

Drilling system 10 is an example of a well operation that employs theimpact attenuating device 100, also referred to herein as an impactattenuator. In some embodiments, impact attenuator may be attached toanother advantageous location, such as, for example, being directlycoupled to drilling deck 14 without a rotary interface 92 or a guidetubes 94 therebetween. A portion or all of impact attenuator 100 may besubmerged in sea water in some installations.

Referring now to FIG. 2, FIG. 3, and FIG. 4, impact attenuator 100includes impact attenuating media assembly 105 installed in an elongatehousing 200. Assembly 105 includes a receiver 110, an attenuator base130 spaced-apart from receiver 110 by a distance D along an attenuationaxis 145, a plurality of parallel, elongate guide members 150 extendingbetween the receiver 110 and the base 130, and a plurality of stacks 160of impact attenuating media. In the exemplary embodiment shown in FIGS.2-4, guide members 150 are solid rods, and, therefore, will also becalled guide rods 150. Each stack 160 is slidingly disposed along one ofthe guide rods 150 parallel to the attenuation axis 145 between thereceiver 110 and the base 130. Thus, receiver 110 and base 130 are endmembers of assembly 105, and attenuation axis 145 extends throughreceiver 110 and base 130. Each stack 160 of impact attenuating mediaincludes a plurality of impact attenuating media elements, which willalso be called resilient members 162, with adjacent resilient members162 separated by a spacer 180. One of a plurality of fasteners 159attaches to each guide rod 150 and is positioned against or adjacentbase 130, helping to hold media assembly 105 together. As shown in FIG.2, assembly 105 includes three impact attenuating media stacks 160 heldon or coupled to three rods 150. Some other embodiments include fewerthan or more than three pair of rods 150 coupled to media stacks 160.For example, some other embodiments may include one, two, four, five,six, or any practical number of pair of media stacks 160 and coupledrods 150. When impact attenuator 100 is installed in drilling system 10,attenuation axis 145 is aligned along mouse hole axis 95 (FIG. 1).

Referring to FIG. 2 and FIG. 3, receiver 110, one of the end members ofassembly 105, includes a central axis 111 aligned with attenuation axis145 and a round receiver plate 115 centered on axis 111. Receiver plate115 includes an upper surface 116 opposite a lower surface 118, acounter-sunk through-hole 117 extending from upper surface 116 throughlower surface 118 for fluid communication, perimeter surface 119extending between upper and lower surfaces 116, 118, and a plurality ofalignment apertures or holes 124 evenly-spaced around the through-hole117. As shown, holes 124 may be through-holes and may have acounter-sunk portion, i.e. an enlarged portion, at upper surface 116.Each hole 124 is sized to receive slidingly one of the guide rods 150.FIG. 2 shows that receiver plate 115 includes one hole 124 for each rod150 of media assembly 105, therefore having three holes 124. Thisreceiver 110 also includes a guide tube 120 extending from the uppersurface 116 to aid in receiving and directing the impact of a movingobject, of which the motion and impact energy is to be absorbed byimpact attenuator 100. Guide tube 120 includes an outside diameter thanmatches the diameter of perimeter surface 119 of receiver plate 115. Inthe assembly of impact attenuator 100, guide tube 120 is located on theopposite side of receiver plate 115 as are media stacks 160 andtherefore extends axially away from the stacks 160. Receiver 110transfers or distributes the dynamic load of an impacting object amongthe stacks 160. Guide tube 120 assists in keeping receiver plate 115oriented perpendicular to attenuation axis 145 and traveling smoothlywithin housing 200 when absorbing an impact from a falling object. Inthis embodiment, receiver plate 115 and surfaces 116, 118 are flat andthrough-hole 117 is aligned on attenuation axis 145 through the centerof surfaces 115, 116. Some embodiments include a resilient disc or aresilient conical insert member located within guide tube 120 andadjacent upper surface 116 of receiver plate 115 to aid in absorbing theimpact, to regulate the movement, or to reduce the rebound of a fallingobject received within receiver 110.

Referring FIG. 5 and FIG. 2, in a simple form, base 130, the other endmember of media assembly 105, is a flat plate and may also be called abase plate or a retainer plate. Base 130 includes an upper surface 132,a lower surface 133 having a chamfered perimeter, a through-hole 134, aplurality of alignment apertures or holes 136 evenly-spaced around thethrough-hole 134. As shown, holes 136 may be through-holes. As such,each hole 136 is sized to slidingly receive or engage one of the guiderods 150 but small enough to block the fastener 159 on lower end 153 ofthat rod 150 from passing-through. In this embodiment, base 130 includesthree holes 136, one for each rod 150 of media assembly 105;through-hole 134 is centrally-located on surfaces 133, 134 with acounter-bore at lower surface 133; and when installed in impactattenuator 100, through-hole 134 is aligned with attenuation axis 145.The perimeter of base 130 is filleted at lower surface 133. Through-hole134 and alignment holes 136 extend through surface 132 and surface 133.Through-hole 134 may provide passage for the transfer of fluid toreduce, relieve, or inhibit the build-up of pressure within impactattenuator 100 during an impact by an object.

Referring again to FIG. 2, FIG. 3, and FIG. 4, guide rod 150 includes anupper end 152, a lower end 153 spaced-apart from upper end 152, and acentral axis 155 extending longitudinally through ends 152, 153. Inmedia assembly 105, upper end 152 threadingly receives a fastener 158,and lower end 153 threadingly receives another fastener 159. Fasteners158, 159 may be internally threaded nuts and may be identical ordifferent.

As stated earlier in reference to FIG. 2, each media stack 160 includesa plurality of resilient members 162 alternating among a plurality ofspacers 180. FIGS. 6A and 6B shows a resilient member 162 in greaterdetail. Due to their generally toroidal shape, resilient members 162 ofimpact attenuating media assembly 105 may also be called impactabsorbing donuts or, supply, donuts 162, and stack 160 may also becalled a donut stack. In at least some embodiments, the resilientmembers 162 may be described as being discs, shaped like a hockey puck.Other embodiments may include resilient members 162 having other shapes,for example a cup-shape having a concave inner surface possibly with aconvex outer surface. Each spacer 180 includes three alignment aperturesor through-holes 188; each hole 188 slidingly receives or engages one ofthe three guide rods 150 of media assembly 105. Each spacer 180 extendsamong the three rods 150 and the three stacks 160. Thus, the threestacks 160 share the spacers 180, which may be called multi-stackspacers. The three stacks 160, including the shared the spacers 180 andthe three groups of resilient members 162, may be also be described as asingle or aggregate stack of impact attenuating media.

A shown in FIGS. 6A and 6B, each donut 162, i.e. the resilient member ofthis embodiment, is characterized by a relaxed-state diameter θ1 (“theta1”) and a relaxed-state height or thickness H1. Donut 162 includes afirst end 163 having a recessed surface, a second end 164 recess surfaceand spaced-apart from surface 163, along a central axis 165 that extendsthrough surfaces 163, 164. Donut 162 further includes an alignmentaperture 166 extending through surfaces 163, 164 and generally alignedon the central axis 165, and includes a disc-shaped interior recess 168also generally axially aligned. Aperture 166 need not be formed at theexact center of the donut 162, but it is generally centrally located andthus aperture 166 is also referred to herein as a central aperture 166.Interior recess 168 intersects central aperture 166 and may also becalled an annular groove. Donut 162 may be, for example, a suspensionpad having the part number SK1129010, made from TECSPAK PER EPCTEEDmaterial by Miner Elastomer Products Corporation of Geneva, Illinois.This material has good resistance to sea water. In an example, therelaxed-state diameter θ1 is 7.28 inches (184.9 mm), the relaxed-stateheight H1 is 2.52 inches (64.0 mm), and the central aperture 166includes a diameter of ranging from 2.09 inches (53.1 mm) to 2.44 inches(62.0 mm).

To prepare for operation, a donut 162 may be partially compressed to apre-loaded state, having a pre-loaded diameter θ2 (“theta 2”) (FIG. 7),as will be discussed subsequently. The dashed lines 170 in FIG. 6B showthe general shape and dimension of donut 162 when it is compressed toits fully-loaded design condition, achieving what may be called a “solidstate.” In this condition, donut 162 has a solid state or fully-loadeddiameter θ3 (“theta 3”) and a solid state or fully-loaded height H3. Inan example, the fully-loaded diameter θ3 is 8.88 inches (225.4 mm) andfully-loaded height H3 is 1.45 inches (36.8 mm). In an example, thefully-loaded diameter θ3 is 122% of the relaxed-state diameter θ1, andthe fully-loaded height H3 is 58% of the relaxed-state height H1. Othervalues for these several parameters of donut 162 are possible.

Referring now to FIG. 7, spacer 180 comprises a spacer plate having afirst surface 182, a second surface 183 opposite the first, a centralaxis, 185 extending perpendicularly through surfaces 182, 183, anaperture or through-hole 186, the plurality of alignment apertures orthrough-holes 188—one for each guide rod 150, and a plurality ofgripping features or, simply, grip elements 190 adjacent each hole 188.Three holes 188 are evenly spaced (both circumferentially and radially)about central axis, 185. In FIG. 7, aperture 186 is aligned along axis185 and may be called a central aperture. The plan view on the left sideof FIG. 7 includes three circles 191, 192, 193 to indicate the locationsfor three donuts 162 to be disposed on the first surface 182 concentricwith each of the three holes 188. The first circle 191 shows theposition of a first donut in a relaxed state, having a diameter θ1. Thesecond circle 192 shows the position of a second donut in a pre-loadedstate, having a pre-loaded diameter θ2 (“theta 2”). The pre-loaded stateis discussed below. The third circle 193 shows the position of a thirddonut in its fully-loaded state, having a diameter θ3. The donutdiameters shown in FIG. 7 are for reference only. Typically, all threeadjacent donuts would be in a similar operational state (i.e. relaxed,fully-loaded, pre-loaded, or an intermediate state) and are anticipatedto have a similar diameter during any particular operating condition ofmedia assembly 105. In the example shown, holes 188 are positioned aboutaxis 185 such that donuts 162 will not contact each other whenfully-loaded, i.e. when all have a diameter similar to diameter θ3 ofcircle 193. One or both surfaces 182, 183 of spacer 180 may besandblasted or otherwise disturbed to give them roughness or to increasetheir roughness, the surface roughness acting as an additional grippingfeature or grip element adjacent alignment holes 188 for donuts 162.

Best seen in the side view of FIG. 7, each grip element 190 is a punchedhole formed with a jagged, torn edge, which may be described as anaxially-extending, annular projection. A plurality of grip elements 190is disposed circumferentially around each alignment hole 188 of thespacer plate 180. Around each hole 188, three grip elements 190projecting axially from the first surface 182, and three grip elements190 project axially from the second surface 183. In some otherembodiments, spacer plate 180 may use fewer or more grip elements, andsome grip elements may be spaced at differing radial distances from hole188. In a media assembly 105, each grip element 190 engages the adjacentdonut 162 to control its rate of expansion or amount of expansion whencompressed in pre-loaded state or when compressed by an impact loadduring operation. Due to the inclusion of grip elements 190, spacer 180may also be called an expansion control device. Spacer 180 may act as acentralizer to keep donuts 162 centrally located about the rod 150 onwhich they are located or may act to keep the stacks 160 centrallylocated around attenuation axis 145. The capability of spacer 180 to actas a centralizer may be advantageous during assembly, storage, shipping,compression, or decompression. Thus, spacer 180 may also be called acentralizer comprising a centralizing plate. Furthermore, the outerperimeter of spacer 180 is located adjacent the circumferential innersurface of housing body 210, being in close proximity to or havingsliding contact with body 210. Thus, spacer 180 extends from guidemembers 150, which are received in alignment holes 188, to the innersurface of housing body 210, extending in a direction perpendicular toattenuation axis 145. Being located in a stack of donuts 162 with thisarrangement, spacer 180 is configured to provide a radial reaction forceto inhibit or prevent buckling of rod 150 and stack 160 during an impactevent, and therefore may also be called a stabilizer. The centralizingand stabilizing features or properties of spacer 180 overlap and are notintended to be exclusive of each other.

In various embodiments, a gripping feature 190 includes any of a varietyof suitable bumps, extensions, projections that are configured andlocated so as to engage a portion of the impact attenuating media andthereby to control the rate or amount of expansion of a resilient memberor donut 162 when compressed. In some embodiments, gripping feature 190penetrates into the surface of donut 162, possibly breaking the surface.In one example, a grip element extends circumferentially around hole188, projecting axially from the first surface 182, and another gripelement extends circumferentially the same hole 188, projecting axiallyfrom the second surface 183. Multiple, concentric grip elements thatextend in the same direction may also be used. In another example,gripping feature 190 may comprise pointed pins coupled to plate 180around each hole 188, each pin extending uni-directionally orbi-directionally, i.e. from one or both surface 182 and surface 183.

Referring again to FIG. 2 and also to FIG. 4, impact attenuator housing200 is elongate and includes a longitudinal axis 205 aligned withattenuation axis 145, a housing body 210 extending along axis 205 from aupper end 212 to a lower end 214, an internal chamber 215 extendingbetween ends 212, 214, a gusseted flange 216 coupled at upper end 212,and a housing base 218 coupled at lower end 214. In the example of FIG.2, housing body 210 is a cylindrical shell, and housing base 218 iscontained within the lower end 214 of housing body 210. Flange 216 maybe replaced by threads or another means of attaching housing 200 toother fixtures. For at least some embodiments, housing base 218 may alsobe called a closure member.

Shown in FIG. 2 and FIG. 8, housing base 218 comprises a circular baseplate 220 centered on axis 205 and having a plurality of alignmentapertures or holes 222 evenly-spaced around axis 205. As shown, holes222 may be through-holes. Base plate 220 includes three holes 222, onefor each rod 150 of media assembly 105. Each hole 222 is large enough toreceive both a rod 150 and a fastener 159 attached to the lower end 153of the rod, allowing these features 150, 159 to move into and throughthe hole 222. In this embodiment, each alignment hole 222 has a diameterlarger than the diameter of a rod 150 and larger than the diameter ofalignment holes 136, 188 of base 130 and spacer 180, respectively.Housing base 218 further includes a tubular central support 224surrounded by a plurality of gussets 226 extending radially and axiallyfrom base plate 220 to central support 224 and to the inner surface ofhousing body 210. A though-hole 228 having a lower, threaded end 229extends through base plate 220 and tubular central support 224,providing a passage way for fluid transfer as will be explained laterwhen discussing fluid zones 250, 252, 254, 256 within impact attenuator100. Threaded end 229 provides a location to couple a hose, a pump, orother fluid transfer equipment to facilitate the movement of fluidthrough the hole 228.

The sectional view of FIG. 9 shows media assembly 105 during the finalstages of assembly prior to installation in the housing 200 (not shown).FIG. 9 shows only two guide rods 150 each with a donut stack 160, butthis conversation applies to the three pair of rods 150 and donut stacks160 of this embodiment (per FIG. 2 and FIG. 3). The upper ends 152 ofthe three guide rods 150 are attached to receiver 110, each by afastener 158 installed in a counter-sunk portion of each hole 124 inreceiver plate 115 and threadingly engaging the guide rod. A sealingwasher may be slidingly received on rod 150 between fastener 158 andreceiver plate 115 to aid in isolating fluid zone 250 from zone 252within impact attenuator 100. Rods 150 are parallel to each otherparallel to attenuation axis 145. To facilitate the assembly process, arod extension 240 is attached or coupled to the lower end 153 of eachrod 150 to form a lengthened guide member. Thus, three rod extensions240 are attached. In this example, a rod extension 240 isaxially-aligned and threadingly coupled to each rod 150. At a selectedlocation along attenuation axis 145, a donut 162 is disposed on each ofthe three rods 150. Axially adjacent these three donuts 162, a singlespacer 180 is slidingly received on all three rods 150. This alternatingarrangement of three donuts 162 located adjacent a spacer 180 isrepeated along the length of the each pair of rods 150 and rod extension240 such that donut 162 engages a spacer 180 on each end 163, 164, andspacer 180 engages three resilient donuts 162 on each spacer surface182, 183 to form the multiple media stacks 160. In this manner, eachspacer 180 is shared as a member of all three media stacks 160. Eachlengthened guide member (i.e. a pair that includes a guide rod 150 and arod extension 240) extends through and is slidingly received or engagedby the central aperture 166 in each donut 162 of the corresponding mediastack 160 and one of the alignment holes 188 in each spacer 180. In thismanner, spacers 180 are shared by all adjacent media stacks 160. The twoends of the stacks 160 terminate with a spacer 180 adjacent the receiver110 and another spacer 180 adjacent the base 130. Terminating the endsof stacks 160 with a spacer 180 rather than a donut 162 may improve theexpansion or contraction behavior of the end-most donuts 162, providinggrip elements 190 on both sides of even these donuts. Various otherembodiments may terminate one or both ends of the stacks 160 with adonut 162 instead. Some of these other embodiments may include gripelements 190 on surfaces of receiver 110 and base 130.

In FIG. 9, each stack 160 extends from receiver 110 to base 130 alongthe corresponding guide rod 150 and the rod extension 240. Thus, eachpair of a rod 150 and a rod extension 240 extends between the receiverand the base and slidingly extends through one of the stacks 160. Base130 is disposed on rod extensions 240 adjacent the right end of stack160, which eventually becomes the lower end in some installations.Fasteners 159 are threaded on the ends of rod extensions 240 to holdbase 130 and stack 160 together on the rods and rod extensions. Theplurality of donuts 162 are in their relaxed state, each having arelaxed-state thickness or height H1 (FIG. 6B). As a result each stack160 of donuts 162 has a relaxed length of L1 in FIG. 9. To prepare theimpact attenuating media assembly 105 for installation in housing 200and for operation, assembly 105 is partially compressed to a pre-loadedstate, reducing the parallel stacks 160 to a pre-loaded length L2between the receiver 160 and the base 130 (shown in FIG. 2 and FIG. 10).To achieve this pre-load, a press (machine not shown) forces the base130 toward receiver 110, partially compressing each donut stack 160 to alength that may be temporarily less than the pre-loaded length L2. Rodextensions 240 are removed and fasteners 159 are installed on the lowerends 153 of guide rods 150. Finally, the press relaxes, and the tensionthat it held, i.e. the pre-load compression force of the many donuts162, is transferred to the frame of media assembly 105, which includesrods 150, base 130, fasteners 159, as well as receiver 110.

In this manner, the arrangement of media assembly 105 shown in FIG. 10(minus the housing 200) may be achieved, and media assembly 105 isconfigured into its pre-loaded or “resting” state. The plurality ofdonuts 162 are in their pre-loaded state, each exhibiting, on average, apre-loaded height and each exerting a pre-load force. The pre-loadedheight of a donut 162 is less than the relaxed-state height H1 andgreater than the fully-loaded height H3 (For H1 and H3, see FIG. 6B).The pre-loaded length L2 of donut stacks 160 is equivalent to andmeasures the same span as the distance D (FIG. 2) between receiver 110and a base 130. In an example, the pre-loaded length L2 of the donutstacks 160 is 257.38 inches (6.5375 m).

Configuring media assembly 105 in a pre-loaded state prepares it toexert more effectively a reaction force to resist, arrest, or absorb,the movement of an object, for example the falling a of string oftubular members. In at least one embodiment, media assembly 105 may bepre-loaded by applying static or quasi-static compression force of 50tons (English units: 2,000 pounds per ton, typical throughout), putting,on average, all donuts 162 in their pre-loaded state and compressing thestacks 160 from length L1 to length L2. The compression force may beapplied to media assembly 105 by using a hydraulic press, for example.The pre-loaded state may be described by a pre-load ratio R_ _(PL)between the pre-loaded length L2 and the relaxed length L1 of donutstacks 160, i.e. R_ _(PL) =L2/L1. In an example R_ _(PL) equals 0.891,which means the length of stack 160 is compressed to 89.1% of itsoriginal, relaxed length L1.

In media assembly 105, each guide rod 150 extends through and isslidingly received by the central aperture 166 of each donut 162 of thecorresponding media stack 160 and one of the holes 188 in each spacer180. In some embodiments, including FIG. 10, each of the three mediastacks 160 includes a quantity of one hundred and nine (109) of thedonuts 162. In some embodiments, including FIG. 10, the media assembly105 includes the three stacks 160 with a total of three hundred andtwenty-seven (327) of the donuts 162. Various other embodiments includefewer or more of the donuts 162, within a practical limit appropriatefor use as described herein.

As shown in FIG. 10 and also FIG. 2, assembly 105 is subsequentlyinstalled into housing 200 through upper end 212, with guide rods 150,receiver 110, base 130, and the multiple stacks 160 of donuts 162coupled together and disposed within chamber 215, forming the impactattenuator 100. Receiver 110 is disposed adjacent the housing upper end212 with guide tube 120 proximal the upper end 212. Lower surface 133 ofbase 130 engages and receives support from housing base 218, at leastwhen impact attenuator 100 is vertical or an impact load is received.Each rod upper end 152 is attached to receiver 110, and each rod lowerend 153 is slidingly received by one of the holes 136 in the base 130,configuring the receiver 110 and the rods 150 to be movable relative tothe base 130 and the housing 200.

Within impact attenuator 100, at least four fluid zones 250, 252, 254,256 may be defined. An upper fluid zone 250 is located in the upper end212 of housing chamber 215 and includes volume within receiver 110. Acentral fluid zone 252 is located in housing chamber 215 betweenreceiver plate 115 and base 130 and includes the many voids 196 betweenpairs of adjacent spacers 180. The voids 196 fluidically communicatewith each other through the apertures 186 of spacers 180 or throughspace located between the perimeters of spacers 180 and housing body210. A lower fluid zone 254 is located at the lower end 214 of housingchamber 215, below housing base plate 220. The fourth zone, which willbe called fluid transfer zone 256, includes the though-hole 228 thatextends through base plate 220 and tubular central support 224 ofhousing base 218. Fluid communication may occur between various pairs orgroups of the zones 250, 252, 254, 256 depending on the seals, hoses,relief passages, or fluid transfer equipment that may be installedadjacent one or more of the four zones in various embodiments. Inembodiments having no such seals, hoses, etc., fluid communication mayoccur between all four zones, directly or indirectly. The volumeoccupied by at least zones 250, 252 is variable, based on the axiallocation of receiver 110.

Within impact attenuator 100, each hole 136 of base 130 is aligned witha hole 222 of housing base 218. Each rod 150 is slidingly received byone of the holes 136 and is aligned with the corresponding hole 222 andis configured to extend the hole 222. In FIG. 2 and FIG. 10, each pairof rod 150 and fastener 159 is disposed in a hole 222. In FIG. 2, FIG.10, and FIG. 11, the rod 150 extends through the corresponding hole 136and hole 222.

In its pre-loaded state, impact attenuating media assembly 105 isinstallable in and removable from the housing 200 as a single unit. Whenmedia assembly 105 and impact attenuator 100 are assembled together in apre-loaded state as shown in FIG. 10 and FIG. 2, impact attenuator 100is ready to be installed in drilling system 10 of FIG. 1 or in anothersystem.

Continuing to reference FIG. 10 and FIG. 2, media assembly 105 includesa plurality of voids 196 extending axially between each pair of adjacentspacers 180 and extending radially between and beyond the three donuts162 that share a common axial position along the axis 145. The pluralityof voids 196 are in fluid communication with each other due to theinclusion of an aperture 186 in each spacer 180. The plurality voids 196and the plurality apertures 186 together may be considered to be asingle void or volume and may contain, for example, air, water, oranother fluid. In FIG. 2, the voids 196 and apertures 186 are in fluidcommunication with though-hole 228 in housing base 218 and withthrough-hole 117 in receiver 110. Therefore, the open, central volume ofthe receiver guide tube 120 is in fluid communication with thethough-hole 228 in housing base 218.

The stacks 160 of donuts 162 are configured to exert a reaction forcewhen an axial force acts to reduce the distance between the receiver 110and the base 130. For example, when a tubular member or another objectfalls into or otherwise impacts receiver 110, media assembly 105compresses further than shown in FIG. 10. The donuts 162 provide areaction force to resist, arrest, or absorb the movement of the object.In the process, receiver 105 moves downward (or rightward, as-shown)from upper end 212 of housing 200 toward the lower end 214, and themedia stack 160 compresses, reducing its length to less than length L2.The lower ends 153 of guide rods 150 and fasteners 159 extend furtherbeyond housing base plate 220 and possibly beyond the housing body lowerend 214. As the falling object comes to a rest, media assembly 105 mayrelax, but maintain some amount of compression to hold the weight of theobject. In at least some instances after capturing a falling object,stack 160 and the receiver 110 rebound some distance before coming torest.

As an example of loading, FIG. 11 shows impact attenuating device 100with the media assembly 105 fully-compressed as it would be whenexperiencing a maximum compression or impact load. In at least oneembodiment, media assembly 105 may be fully-compressed or fully-loadedby applying a static or quasi-static compression of force of 450 tons,putting, on average, all donuts 162 in their fully-loaded state “solidstate,” as introduced earlier with respect to FIG. 6B and FIG. 7. InFIG. 11, the plurality of donuts 162 are in their fully-loaded state,each exhibiting, on average, the fully-loaded height H3. As a resultdonut stack 160 has a fully-loaded length L3, which includes the donuts162 and spacers 180. The lower surface 118 of receiver 105 (i.e. the topof stack 160) is displaced by a distance or length L4 from upper end 212of housing 200, the distance L4 in FIG. 11 being greater than the“relaxed” at-rest distance or length L5 between the same two locationsin FIG. 10, i.e. the distance between lower surface 118 of receiver 105and upper end 212 of housing 200. Continuing to reference FIG. 11, rods150 extend beyond housing base plate 220 and beyond housing body lowerend 214. The configuration of FIG. 11 demonstrates the maximum movement,i.e. the maximum compression, of media assembly 105. The fully-loadedstate may be described by a fully-loaded length ratio R_ _(FL) betweenthe fully-loaded length L3 and the relaxed length L1 of donut stacks160, i.e. R_ _(FL) =L3/L1. In an example R_ _(FL) equals 0.600, whichmeans the length of stack 160 is compressed to 60.0% of its relaxedlength L1.

A comparison between the pre-loaded state and the fully-loaded state maybe helpful for understanding the configuration of the exemplary mediaassembly 105 and device 100 further. A length ratio R_ _(FP) may bedefined as the ratio between the fully-loaded length L3 and thepre-loaded length L2 of donut stacks 160, i.e. R_ _(FP) =L3/L2. Ratio__(FP) represents the maximum additional compression that media assembly105 may achieve during assembly or operation. In an example R_ _(FP)equals 0.674, which means the length of stack 160 would be compressed to67.4% of its pre-loaded length L2 to achieve the fully-loaded length L3.The parameter R_ _(C) will be defined as the ratio of the compressionforce needed to achieve a fully-loaded state versus the compressionforce needed to achieve a pre-loaded state. In an example, R_ _(C) is9.00 (450 tons/50 tons), at least when the forces are applied staticallyor quasi-statically.

Typically, impact attenuating device 100 would be configured so thatassembly 105, stacks 160, and donuts 162 would not reach thefully-loaded state shown in FIG. 11 when impacted by a maximumanticipated, dynamic load, which may be called the maximum design loador the selected load capacity. A maximum design load specifies, forexample, a gravitationally-driven fall by the heaviest anticipatedobject through the greatest anticipated height that is intended to bedissipated or transferred by device 100. It is anticipated that animpact equal to the maximum design load will leave device 100 in are-usable condition. The maximum design load is selected based onoperational needs and is implemented in device 100 by standardengineering principles. Device 100 might achieve the fully-loaded stateif dynamically impacted by an object weighing more than or impacted byan object falling farther than is specified by the maximum design load.Device 100 may or may not remain in a re-usable condition after animpact that achieves the fully-loaded state.

Referring to FIG. 12, in another embodiment, a spacer 280 is designed tobe slidingly received on a single guide rod 150 and to engage a singlestack of donuts 162. Thus, spacer 280 may be called a single-stackspacer. Spacer 280 comprises a spacer plate having a first surface 282,a second surface 283 opposite the first, an axis, 285 extendingperpendicular to surfaces 282, 283, a single alignment aperture orthrough-hole 188 that is centered on axis 285, and at least one gripelement 190 adjacent the hole 188. As before, each grip element 190 is apunched hole formed with a jagged, torn edge, which may be described asan axially-extending, annular projection. More specifically, in the FIG.12, a plurality of grip elements 190 circumferentially surround the hole188, with some grip elements 190 extending in a first direction awayfrom first surface 282 and others extending in a second direction, awayfrom second surface 283. As explained with regard to spacer 180, so alsofor spacer 280, other types of grip elements may be used. Although theouter edge of spacer 280 is shown a circular, other shapes may be used,and axis 285 may be in the center of the plate or may be off-set;similar variations may be applied to spacer 180. Due to the inclusion ofgrip elements 190, spacer 280 may also be called an expansion controldevice. During compression and decompression activity, spacer 280 mayalso act as a centralizer to keep donuts 162 centrally located about therod 150 on which they are located. Thus, spacer 280 may also be called acentralizer comprising a centralizing plate.

Spacer 280 differs from spacer 180 because each spacer 280 includes asingle alignment hole 188 and therefore slidingly receives or engagesonly one guide rod 150. When a plurality of spacers 280 are used in animpact attenuating media assembly having multiple rods 150, the stacksof impact attenuating media that are formed around each rod 150 may beseparate, not interconnected to other stacks by a spacer. When spacers280 are used to form a media assembly like media assembly 105 for usewithin the impact attenuator 100, three spacers 280 are used in place ofeach spacer 180, and a guide rod 150 extends through the centralaperture 166 of each donut 162 (i.e. the resilient member) and thealignment hole 188 of each spacer 280. Consequently, three, independentstacks of impact attenuating media are formed, one stack coupled to anddisposed around each rod 150, each stack having its own group of spacers280. In contrast, in FIG. 2 and FIG. 9 the shared spacers 180interconnect in the three stacks 160 of donut 162 that accompany thethree rods 150. A stack of impact attenuating media formed withplurality of dedicated spacers 280 comprises a plurality of donut 162alternately stacked among the spacers 280. Except perhaps at the ends ofthe stack, each spacer 280 is disposed between two adjacent donuts 162.On spacer 280, grip element 190 engages a surface of at least oneadjacent donut 162.

FIG. 13 and FIG. 14 present another embodiment of an impact attenuatingdevice. Impact attenuator 300 of FIG. 13 and FIG. 14 is similar toimpact attenuator 100; however, impact attenuator 300 includes an impactattenuating media assembly 305 having four parallel guide members orguide rods 150 instead of three, and various other features are modifiedto accommodate the extra rod 150. Impact attenuating media assembly 305also includes four impact attenuating media stacks 360; one stack isheld on or is coupled to each of the four rods 150. Assembly 305 furtherincludes a receiver 310 attached to the ends of the four guide rods 150and an attenuator base 330 slidingly coupled to the opposite ends of thefour guide rods 150. For this purpose, base 330 includes an additionalalignment aperture or hole, giving it four holes 136, which arethrough-holes, and each hole 136 slidingly receives or engages one ofthe guide rods 150. Most other aspects of media assembly 305 are similarto corresponding features of impact attenuating media assembly 105. Forexample, most other aspects of base 330 are similar to base 130. Mostother aspects of receiver 310 are similar to receiver 110, for example,receiver 310 includes a receiver plate 115 and a guide tube 120.

Continuing to reference FIG. 14 briefly, each stack 360 includes aplurality of impact attenuating media elements or resilient members,which in the embodiment are donuts 162, alternating among a plurality ofmulti-stack spacers 380. Each spacer 380 includes four alignmentapertures or through-holes 188, each hole 188 slidingly receiving one ofthe four guide rods 150. Each spacer 380 extends among the four rods 150and the four stacks 360. Thus, in impact attenuating media assembly 305,the four media stacks 160 share each of the spacers 380. The four stacks160, including the shared the spacers 180 and the four groups of donuts162, may be also be described as a single or aggregate stack of impactattenuating media.

Referring now to FIG. 15, spacer 380 comprises a round spacer platehaving a first surface 382, a second surface opposite the first, acentral axis 385 extending perpendicular to the first and secondsurfaces, a central aperture or through-hole 186 aligned along axis 385,the four holes 188, and a plurality of gripping features or, simply,grip elements 190 adjacent each hole 188. The alignment holes 188 areevenly spaced (both circumferentially and radially) about central axis385. In the embodiment shown, holes 188 are designed to be positionedabout axis 385 such that donuts 162 will not contact each other whenfully-loaded, i.e. when and if all donuts 162 adjacent a spacer 280 haveexpanded to a diameter θ3 (“theta 3”) like circle 193 of FIG. 7.

Similar to spacer 180, around each alignment hole 188 of spacer 380,three grip elements 190 projecting axially from the first surface 382,and three grip elements 190 project axially from the second surface. Insome other embodiments, a spacer plate may use fewer or more gripelements, and some grip elements may be located or spaced atdifferently. The grip elements 190 are similar to those describedpreviously and similarly engage adjacent donuts 162 to control theirrate of expansion or amount of expansion when compressed in pre-loadedstate or when compressed by an impact load during operation. Due to theinclusion of grip elements 190, spacer 380 may also be called anexpansion control device. During compression and decompression activity,spacer 380 may also act as a centralizer to keep donuts 162 centrallylocated about the rod 150 on which they are located or may act to keepthe stacks 360 centrally located around attenuation axis 345. Thus,spacer 380 may also be called a centralizer comprising a centralizingplate.

Continuing to reference FIG. 14, impact attenuator 300 further includesan impact attenuator housing 400 having a longitudinal axis 405, acylindrical shell or housing body 210, and a housing base 418. Housingbase 418 includes a circular base plate 420 with an extra alignment holeand an extra gusset 226, but is otherwise similar to housing base 218 ofFIG. 2 and FIG. 3.

In the assembled impact attenuator 300 of FIG. 14, impact attenuatingmedia assembly 305 is slidingly received within housing 400. Thus, guiderods 150, the receiver 310, the base 330, and the four stacks 360 ofdonuts 162 are disposed within housing 400 with the lower surface ofbase 330 engaging and receiving support from housing base 418. FIG. 14shows pre-loaded, “resting” condition of impact attenuator 300, whereinit is ready to be installed in drilling system 10 (FIG. 1) or in anothersystem. The plurality of donuts 162 are in their pre-loaded state, eachexhibiting, on average, a pre-loaded height.

The single-stack spacer 280 of FIG. 12 is compatible with impactattenuator 300 with four of the spacers 280 being used in place of eachmulti-rod spacer 380. In such embodiments, each of the four stacks 360includes its own group of single-rod spacers 280 alternating betweendonuts 162.

Referring now to FIG. 16, a rectangular, multi-stack spacer 480 issimilar to the round spacer 380. For example, like spacer 380, spacer480 includes spacer plate having central axis 485, central aperture orthrough-hole 186, four alignment apertures or through-holes 188, and aplurality of grip elements 190 adjacent each hole 188. Spacer 480differs from spacer 380 in having a rectangular perimeter, and, for atleast some embodiments, holes 188 of spacer 480 are located further fromcentral axis 385. In this example, spacer 480 is, more precisely, asquare. An impact attenuating device or, equivalently, an impactattenuator that utilizes rectangular spacer 480, may include otherrectangular features as well, such as a rectangular housing body inplace of cylindrical housing body 210, or a rectangular receiver inplace of circular receiver 310, or a rectangular base receiver in placeof circular base 130, for example. Various embodiments designed toutilize spacer 480 may instead include four of the single-stack spacers280 in place of each multi-stack spacer 480. Spacer 480 may also becalled a centralizer comprising a centralizing plate.

FIG. 17 presents a receiver 510 coupled to an attenuator base 530 by abillow hose 520 for fluid communication. A resilient insert member 540is installed within receiver 510. Receiver 510 includes a central axis111, a round receiver plate 115 centered on axis 111, and a guide tube120 coupled to receiver plate 115. Receiver plate 115 includes an uppersurface 116 opposite a lower surface 118, a counter-sunk through-hole117 extending from upper surface 116 through lower surface 118 for fluidcommunication, and a plurality of countersunk alignment apertures orholes 124 evenly-spaced around the axially aligned through-hole 117.Guide tube 120 extends away from upper surface 116, distal base 530 andincludes two grooves 514A, 514B in perimeter surface 516, each groovereceiving an annular seal 518. The two seals 518 may be, for example, apolypack-type seal having a lip that protrudes diagonally outward fromthe main body of the seal. The upper groove 514A receives a first seal518A oriented with an upward-facing lip, the lip extending away fromreceiver plate 115, and the lower groove 514B receives a second seal518B oriented with an downward-facing lip, the lip extending towardreceiver plate 115. In some embodiments, both seals 518 are received ina single groove 514. Thus, receiver 510 is similar to receivers 110, 310with the inclusion of various additional features described here orshown in FIG. 17.

Resilient insert member 540 includes a cylindrical outer surface 542 andconical inner surface 543, and a central through-hole 544. Resilientinsert member 540 is positioned within receiver guide tube 120, abuttingupper surface 116 of receiver plate 115 to aid in absorbing the impact,to regulate the movement, or to reduce the rebound of a falling objectreceived within receiver 110. Resilient insert member 540 may protectthe object that is dropped, such as possibly reducing damage to athreaded end. The through-hole 544 provides fluid communication withbaffle hose 520 through upper end 522.

Base 530, which may also be called a base plate or a retainer plate,includes a through-hole 134 and a plurality of alignment apertures orholes 136 evenly-spaced around the through-hole 134. Thus, base 530 issimilar to base 130 and base 330, and the number of holes 136 may bechosen to allow base 530 to replace either base 130, 330 or to form adistinct embodiment. Through-hole 134 is countersunk from the bottom.

Billow hose 520 includes a first or upper end 522, a second or lower end523, an undulated or billowed hose body 524 extending between the ends522, 523, and two flanges 526, one flange coupled at each end 522, 523.The flexible hose body 524 is extendable and contractible to accommodatethe changeable distance D between receiver plate 115 and base 530. Theupper end 522 of hose 520 and the corresponding flange 526 are sealinglyreceived in the countersunk through-hole 117 in receiver plate 115.Likewise, the lower end 523 and its flange 526 are sealingly received inthe countersunk through-hole 134 of base 530.

The arrangement of FIG. 17 may be used in an impact attenuating mediaassembly 105 or an impact attenuating media assembly 305 in place of thecorresponding receiver 110, 310 and base 130, 330 and installed in ahousing 200 to form alternate embodiments of impact attenuators 100,300. A plurality of donut stacks 160 and guide rods 150 would be heldbetween receiver 510 and base 530. Referring to the fluid zones of FIG.2 and FIG. 14, the billow hose 520 and the seals 514A, B of FIG. 17 areconfigured to provide fluid communication between upper fluid zone 250and the fluid transfer zone 256 of hole 228 while at the same timeisolating these two zones from direct communication with central fluidzone 252. When a hose or a pump, for example, is coupled to threaded end229 of hole 228, fluid zones 250, 256 may be fully isolated from boththe central fluid zone 252 and the lower fluid zone 254. An additionalseal or connecting member may be used to achieve fluid zone isolation.For example, a sealing member, such as a resilient O-ring or gasket, maybe positioned between lower surface 133 of base 130 and the uppersurface of housing base plate 220, and base plate 220 may be welded totubular central support 224 to achieve the isolation of fluid zones 250,256 from fluid zones 252, 254.

With fluid zones 250, 256 fully isolated as described, a well drillingfluid from may enter the mouse hole 90 through drilling deck 14 (FIG. 1)be contained, preventing, i.e. stopping or reducing the potential for, arelease to the environment. The well drilling fluid may includehydraulic oil or drilling mud, as examples. Some embodiments includerelief passages or other flow area in housing base 218 to provided fluidcommunication between central fluid zone 252 and the lower fluid zone254, allowing, air or sea water to readily flow into and out of centralfluid zone 252 when the impact attenuator receives a falling object orwhen an received object is later removed, helping the donut stacks andvoids 196 to be compressed or to re-expand without sustaining pressureor vacuum in zone 252.

At least one embodiment having features shown in FIG. 1 as well as FIG.2 or FIG. 14 includes a drilling apparatus having a drilling floor, amouse hole in the drilling floor, an elongate housing supported in aposition below the drilling floor and comprising an internal chamberpositioned beneath the mouse hole, and at least a first impactattenuating stack disposed in the chamber. The first impact attenuatingstack includes a plurality of resilient members disposed along a rod,each resilient member having an alignment aperture and receiving the rodtherethrough; and includes a plurality of spacers disposed betweenadjacent resilient members, each spacer having an alignment hole andreceiving the rod therethrough.

In at least some of these embodiments, the drilling apparatus furtherincludes a plurality of impact attenuating stacks disposed generallyparallel to one another in the chamber, each impact attenuating stackincludes a plurality of the resilient members disposed along a rodhaving an alignment aperture and receiving the rod therethrough, and aplurality of the spacers disposed between adjacent resilient members,each spacer having an alignment holes and receiving the rodtherethrough.

In at least some of these embodiments, each impact attenuating stackfurther includes: a first end member, a second end member spaced adistance D from the first end member and having an alignment holetherethrough; and the rod is attached to the first end member and isslidingly received through the alignment hole in the second end member.

FIG. 18 and FIG. 19 present another embodiment of an impact attenuatingdevice compatible with mouse hole 90 of drilling system 10 and withother well systems. Impact attenuator 600 includes an impact attenuatingmedia assembly 605 designed to absorb impacts along an attenuation axis606, an impact attenuator housing 670, and a containment vessel or tube680. Media assembly 605 includes a receiver 610, an attenuator base 620spaced-apart from receiver 610, a single, tubular guide member 630instead of a plurality of members 150. The elongate guide member 630extends from receiver 610 and into base 620 along axis 606. Impactattenuating media assembly 605 also includes a single impact attenuatingmedia stack 650, located along member 630, centered on axis 606.

Receiver 610 is similar to receivers 110, 310. Receiver 610 includes areceiver plate 612 and a guide tube 120, and plate 612 includes acentral aperture 615. Base 620 is a flat plate and may also be called abase plate or a retainer plate. Base 620 includes a central alignmentaperture or through-hole 622 also aligned on axis 606.

Referring to FIG. 18 and FIG. 20, tubular guide member 630, whichincludes an upper end 631 and a lower end 632, is a member of a guidemember assembly 625. In addition to member 630, guide assembly 625includes an upper end plate 634 coupled at upper end 631 and a fastenerassembly 635 coupled at lower end 632. As best seen in FIG. 20, fastenerassembly 635 includes an interior sleeve 636 held within the hollow,lower end 632, and a stop-washer 637 coupled to the lower ends of sleeve636 and member 630 by a fastener 638.

Referring again to FIG. 18, end plate 634 is held adjacent the uppersurface of receiver plate 612, and, in this embodiment, plate 634 isheld against a shoulder within aperture 615. Plate 634 allows member 630to be inserted through receiver plate 612 prior to the addition ofstop-washer 637 and fastener 638. Plate 634 limits any further downwardmovement (to the right as depicted) of member 630 with respect toreceiver 610. End plate 634 and fastener assembly 635 are configured tohold the entire media assembly 605 together, allowing it to be insertedor removed from housing 670 as a single unit.

Referring again to both FIG. 18 and FIG. 20, aperture 622 in base 620 issized to slidingly receive guide member 630 but small enough to blockthe fastener 638 and stop-washer 637 on the lower end 632 frompassing-through the aperture 622. For example, washer 637 may be round,having an outside diameter D637 that is greater than the diameter ofaperture 622. Member end 632 may alternately extend further below thebase 620 and then return upward as media stack 650 compresses andpossibly re-expands due to the impact of a falling tubular membercaptured within receiver 610. Fastener assembly 635 keeps member 630coupled to base 620 and limits the upward movement (to the left asdepicted) of member 630 with respect to base 620.

Continuing to reference FIG. 18, media stack 650 includes a plurality ofimpact attenuating media elements or resilient members, which in theembodiment are generally flat toroids or donuts 652, placedside-by-side, each contacting one or two neighboring donuts. Positionedalong member 630, multiple groups of donuts 652 are separated bystabilizers 660. Donuts 652 are flat and solid, in at least theembodiment shown, unlike donuts 162 (FIG. 6B), which includes recessedsurfaces on ends 163, 164 and an interior recess 168. In the example ofFIG. 18, a stabilizer 660 is positioned between groups of nineteendonuts 652, and the centralizers are spaced-apart from plates 612, 620along axis 606 and member 630. A donut 652 rests against each of theplates 612, 620. Plates 612, 620 and guide member assembly 625 hold thedonuts 652 and stabilizers 660 together in the unified assembly 605. InFIG. 21, stabilizer 660 comprises a round, flat plate having a centralalignment hole 662, and a plurality of holes 664 located near theperimeter. Holes 664 are useful as handling locations during maintenanceand installation. Alignment hole 662 slidingly receives guide member630, and the outer perimeter of stabilizer 660 is located adjacent thecircumferential inner surface of housing body 210, being in closeproximity to or having sliding contact with body 210. Thus, stabilizer660 extends from guide member 630 to inner surface of housing body 210,perpendicular to axis 672. In various embodiments, a clearance gapexists between all or a portion of the perimeter of stabilizer 660 andhousing body 210, so as to reduce friction and/or allow communicationtherebetween for air or another fluid. Stabilizer 660 is configured toprovide a radial reaction force to inhibit or prevent buckling of guidemember 630 and stack 650 during an impact event. The use of multiplestabilizers 660 is intended to improve the effectiveness of thesemembers. In the example shown, holes 664 lie radially beyond the donuts652, at least when the donuts are in their relaxed, uncompressed stateor prior to the donuts achieving a fully-loaded state. Holes 664 providepaths for fluid communication within housing 670, allowing air oranother fluid to pass through stabilizers 660 as stack 650 compressesand the voids between stabilizers 660 and plates 612, 610 become smallerduring an impact event.

In the embodiment shown in FIG. 18, the media assembly 605 of attenuator600 is not pre-loaded with a compression force when assembled andprepared for operation. Instead, the donuts 652 remain in their relaxed,uncompressed stated, except for any loading that results from the weightof receiver 610 or other coupled members when media assembly 605 ispositioned vertically. The lack of a pre-load force in the assembly mayprovide manufacturing and handling benefits and results in the use offewer donuts to achieve a maximum design load.

As described above, stack 650 does not include spacers between each pairof adjacent donuts 652. Instead, as shown in FIG. 22, each donut 652includes a central aperture 654 having a plurality of radially-inwardprotrusions 655 that touch or nearly touch guide member 630, which isslidingly received within aperture 654. Protrusions 655 are configuredas centralizers, integral with the body of donut 652 to keep it centeredor substantially centered about member 630 (i.e. is centered or iscentered within a distance of +/−10% of the outer diameter of donut652). In the example shown, there are eight protrusions 655 evenlyspaced in the circumferential direction, and aperture 654 is generallystar-shaped due to the triangular shape of protrusions 655. Donut 652has an outside diameter that is less than the diameter of stabilizers660 and less than the inner diameter of housing 670. In the example ofFIG. 22, protrusions 655 extend radially inward for a distance of 20% ofthe outermost diameter of aperture 654, and the volume of each space issubstantially equal (i.e. equal or within +/−10%) to the volume of eachprotrusion 655. Other proportions for the spaces and the protrusions arecontemplated. For example, in various embodiments, the protrusions 655extend radially for a distance of 5 to 40% of the outermost diameter ofaperture 654.

The spaces or voids between adjacent protrusions 655 provide locationsfor the material of donut 652 to expand radially inward when it iscompressed axially. Donut 652 also expands radially outward towardhousing 670 when compressed axially due to an impact. Preferably, theannular gap 658 between the relaxed donut and inside surface of housing670 is sufficiently large so that donut 652 does not touch housing 670when expanded radially. FIG. 23 is a top view of donut 652, shownfilleting 656 around the perimeter and along aperture 654, as may beformed for embodiments that are injection molded for example. Someembodiments of donut 652 may be formed as flat discs cut from a sheet ofresilient material and lacking filleting 656.

Referring again to FIG. 18 and FIG. 19, housing 670 includes alongitudinal axis 671, a top end 672, a lower end 673 space-apart fromend 672 along axis 671, a cylindrical shell or housing body 210extending between ends 672, 673 and centered about axis 671, and ahousing base 674. Housing base 674 includes a housing base, which, inthis example, is a circular base plate with a central, alignment hole675. Hole 675 is large enough to allow the stop-washer 637, fastener638, and member lower end 632 to pass easily therethrough. At top end672, an annular flange 676 supported by gussets is coupled to body 210and configured to attach below a mouse hole or similar structure at awell. Referring now to FIG. 18, a circular barrier plate 678 spansradially across the entirety of flange 676 to act as a seal to preventthe entry of fluids and debris into housing 670 and impact attenuator600 as a whole when the unit is waiting for a tubular member to fall.During operation, a falling tubular member would typically rupture andpass through the barrier plate 678 prior to impacting the receiver plate612. Later, barrier plate 678 would be replaced.

Below housing 670, coupled and sealed at base 674, containment tube 680extends downward and terminates at a closed lower end 683. Containmenttube 680 may also be called a receiver can or a barrel. The innerdiameter and length of tube 680 are sized larger than the portion ofguide member assembly 625 that passes through housing base 674 during animpact event. Like plate 678 at the upper end of housing 670, tube 680at the lower end of housing 670 prevents the entry of fluids and debrisinto impact attenuator 600. This function of tube 680 is particularlyuseful when attenuator 600 is submerged beneath water. Tube 680 alsohelps to surround and contain the moving members of attenuator 600 toprevent injury to personnel and property. Unlike plate 678, tube 680 isnot physically impacted or damaged during normal operation. In someembodiments, a fluid sensor, such as a float device for liquids forexample is coupled to tube 680 to detect an intrusion of fluid fromoutside tube 680.

Impact attenuating media assembly 605 is configured to be assembledseparately from housing 670. In the assembled impact attenuator 600 ofFIG. 18, impact attenuating media assembly 605 is received withinhousing 670. Receiver 610, base 620, guide member assembly 625, and thestack 650 of donuts 652 are disposed within housing 670 with the lowersurface of base 620 resting on housing base 674. Barrier plate 678covers the receiving end of attenuator 600, corresponding to housingupper end 672. FIG. 18 shows non-loaded, “resting” condition of impactattenuator 600, ready to be installed in drilling system 10 (FIG. 1) orin another system.

Referring now to FIG. 24, an impact attenuating media element 702 is aresilient member shaped like a donut. This impact absorbing donut 702includes a flat end surface 703, a second, flat end surface (not shown)spaced-apart from surface 703 along a central axis 705 and includes analignment aperture or hole 706 extending through the end surfaces andgenerally aligned on the central axis 705. End surface 703 and theopposite end surface each include a plurality of recesses 708. Recesses708 are positioned and sized to receive one of the grip elements 190 ofa spacer, such as a spacer 180, 280, 380, 480, for example. In theexample, donut 702 includes three, equally spaced recesses 708,positioned circumferentially around axis 705 and hole 706. Thus, donut702 is flat and solid, except for central hole 706 and recesses 708, butother embodiments may include an interior recess 168 (FIG. 6B).

A plurality of donuts 702 may be assembled in to a donut stack for animpact attenuating media assembly, like any of those disclosed above,including media assemblies having one, two, three, or more donut stacks.As an example, when assembled in a stack 160 for a media assembly 105(FIG. 2), donuts 702 are pre-loaded, as described of donuts 162.However, in some embodiments, donuts 702 are not pre-loaded whenassembled and prepared for operation. In other respects, these relaxedassemblies may be similar to media assembly 105 or another assemblydisclosed herein.

In an assembly, adjacent donuts 702 are separated by a spacer, such as aspacer 180, 280 (FIG. 7, 12), as examples. Recesses 708 receive gripelements 190, allowing the surface 182, 183, 282, 283 of the spacer torest immediately against an end surface of the donut without a gap,before any pre-load force or any impact load is received. In thismanner, for a selected quantity of donuts assembled without a preloadingforce, a stack of donuts 702 and spacers is shorter than a similar stackthat uses spacers along with donuts lacking end surface recess 708, suchas a donut 162, for example. In addition, alignment hole 706 is largerthan a guide member received therein, allowing free movement relative tothe rod or tubular member. Hole 706 is sized so that it will notcircumferentially touch or grip a guide member, even when the mediaassembly reaches a full-loaded state, leaving some space between thewall of hole 706 and the guide member. In some embodiments, that spacewill extend circumferentially even at the fully-loaded state. Typically,the fully-loaded state results from absorbing an impact that is greaterthan the maximum design load

During operation, air inside an impact attenuator 100, 600 may becompressed as the impact attenuating media assembly compresses under theweight of a falling object. For various embodiments that includecontainment vessel, such as tube 680 in FIG. 18, air inside the vesselmay be compressed as a rod or tubular guide member extends into thevessel. As described for impact attenuator 100, so also various otherembodiments include fluid communication passages or clearance gapsbetween various members to allow air or another fluid to escape from orreturn to the several air pockets inside the impact attenuator,optionally including the containment vessel if it is attached. Someembodiments retain the compressed air during an impact.

Additional Information

Examples of various embodiments have been presented. Some possiblevariations or additional embodiments are described next. Additionalembodiments may share compatible characteristics of one or more of thepreviously-described embodiments or those described below. In variousembodiments, where feasible based on design and operation needs, theguide members that were described as rods may be replaced by tubularmembers, and the guide members that were described as tubular membersmay be replaced by rods.

In assembly 105 of FIG. 2, guide rods 150 are attached to receiver 110by threaded fasteners 158, but in various other embodiments, guide rods150 are attached to receiver 110 by welding, by threads formed inreceiver plate 115, or by any other suitable means known in the art.Although apertures 186 of spacers 180, 380 were axially-aligned, centralapertures, other spacer embodiments having multiple alignment holes 188may include apertures not aligned on a central axis of the spacer.Although shown as a flat plate in FIG. 2 and FIG. 5, in various otherembodiments, the end member or base 130 of assembly 105, may includeadditional structural features such as support ribs, walls,reinforcements around holes, grooves and other such features as may beuseful or may have a shape that is not similar to a flat plate.

In comparison to housing base 218 of FIG. 2 and FIG. 3, some embodimentshave a housing base that comprises a tubular central support 224surrounded by a plurality of gussets 226 without a circular base plate220. The space between gussets 226 provides passageways through whichthe guide rods 150 of assembly 105 may extend during operation.

Various embodiments of an impact attenuating media assembly may includemore than one type of spacer. For example, a modification of betweenimpact attenuating media assembly 105 of FIG. 2 and FIG. 10 may includea plurality of groups of three spacers 280 in place of some of thespacers 180 in the three donut stacks 160. As a more specific example, agroup of three spacers 280 may take the place of every-other spacer 180between alternating pairs of adjacent donuts 162 with several donuts 160contacting a spacer 180 on the first ends 163 and contacting a spacer280 on the second ends 164. Spacers 280 may likewise installed inparallel stacks of resilient members along with spacer 380 or spacer480. It would also be possible to form an impact attenuating mediaassembly with four parallel stacks of resilient members and having botha plurality of spacers 380 and a plurality of spacer 480 to separate orcentralize the resilient members.

As explained in regard to spacers 180, any of the spacers 280, 380, 480may likewise be configured as stabilizers to provide a radial reactionforce to prevent the buckling of a guide member or members and a stackof impact attenuating media. In such embodiments, the spacer 280, 380,480 extends from guide members 150 to the inner surface of a housingbody, extending in a direction perpendicular to attenuation axis 145,the perimeter of the spacer being located in close proximity to orhaving sliding contact with the housing body.

Referring again to FIG. 18, some media stacks embodiments for use inattenuator 600 include spacers, such as spacers 280 of FIG. 12 forexample, located between adjacent donuts, such as any of the donuts 162,652, 702. Donuts 652 with inward protrusions 655 may be used, with orwithout spacers, in embodiments of the other media stacks 105, 305disclosed herein.

While exemplary embodiments have been shown and described, modificationsthereof can be made by one of ordinary skill in the art withoutdeparting from the scope or teachings herein. The embodiments describedherein are exemplary only and are not limiting. Many variations,combinations, and modifications of the systems, apparatus, and processesdescribed herein are possible and are within the scope of thedisclosure. Accordingly, the scope of protection is not limited to theembodiments described herein, but is only limited by the claims thatfollow, the scope of which shall include all equivalents of the subjectmatter of the claims.

1. An impact attenuating device comprising: an elongate housingcomprising first and second housing ends, an internal chamber, and ahousing base spaced-apart from the first housing end; an attenuator basedisposed in the housing and spaced-apart from the first housing end; anda first vertically oriented stack of impact attenuating media disposedin the chamber at a location between the first housing end and theattenuator base, the stack comprising a plurality of resilient members;and an elongate guide member attached to the first housing end andslidingly received by an alignment aperture in the attenuator base;wherein the guide member is slidingly received within apertures in theresilient members.
 2. (canceled)
 3. The impact attenuating device ofclaim 1 comprising: a receiver disposed in the housing adjacent thefirst housing end; wherein the attenuator base includes an alignmentaperture; and wherein the first end of the guide member is attached tothe receiver, and the second end of the guide member is slidinglyreceived by the alignment aperture of the attenuator base, the receiverand the guide member being movable relative to the attenuator base andthe housing.
 4. The impact attenuating device of claim 3 wherein theplurality of resilient members are in a partially compressed state anddisposed between the receiver and the attenuator base.
 5. The impactattenuating device of claim 1 further comprising a plurality of spacerswithin the first stack, each spacer including a plurality of gripelements that extend into at least one of the resilient members.
 6. Theimpact attenuating device of claim 5 further comprising: a receiverdisposed in the housing adjacent the first housing end; an elongateguide member attached to the receiver and slidingly received by analignment aperture in the attenuator base; and an alignment aperture ineach resilient member: wherein each spacer comprises a centralizingplate that includes an alignment aperture; and wherein the guide memberis slidingly received within the alignment apertures of the resilientmembers and the alignment apertures of the centralizing plates.
 7. Theimpact attenuating device of claim 6 wherein the receiver comprises: areceiver plate and a guide tube extending axially from the receiverplate in a direction away from the first stack; and wherein the impactattenuating device further comprises a resilient insert member receivedwithin the guide tube and disposed adjacent the receiver plate, theresilient insert member including a conical inner surface.
 8. The impactattenuating device of claim 1 further comprising: a receiver disposed inthe housing adjacent the first housing end, wherein the receivercomprises: a receiver plate; and a guide tube extending axially from thereceiver plate in a direction away from the stack.
 9. The impactattenuating device of claim 1 further comprising: a receiver disposed inthe housing adjacent the first housing end; a plurality of elongateguide members attached to the receiver, each guide member extendingthrough one of a plurality of alignment apertures in the attenuatorbase; a plurality of stacks of impact attenuating media, including thefirst stack, each stack comprising a plurality of resilient members anda plurality of spacers, wherein each spacer is disposed between adjacentresilient members, wherein each stack is disposed in the chamber betweenthe receiver and the attenuator base; an aperture in each resilientmember, each aperture receiving one of the guide members therethrough;and wherein each spacer in the plurality of spacer comprises a firstalignment aperture receiving one of the guide members therethrough. 10.The impact attenuating device of claim 9 wherein each spacer includes aplurality of alignment apertures, including the first alignmentaperture, each alignment aperture receiving one of the guide memberstherethrough; and wherein each spacer is disposed between adjacentresilient members in each stack.
 11. The impact attenuating device ofclaim 9 wherein the receiver, the attenuator base, the plurality ofguide members, and the plurality of stacks are coupled together as anassembly that is configured to be installable in and removable from thehousing as a single unit.
 12. A drilling apparatus comprising: adrilling floor; a mouse hole in the drilling floor; an elongate housingsupported in a position below the drilling floor and comprising aninternal chamber positioned beneath the mouse hole; and at least a firstimpact attenuating stack disposed in the chamber and comprising: aplurality of resilient members disposed along an elongate guide member,each resilient member including an alignment aperture and receiving theguide member therethrough.
 13. The drilling apparatus of claim 12wherein the first impact attenuating stack further comprises a pluralityof spacers, each spacer including an alignment aperture and receivingthe guide member therethrough.
 14. The drilling apparatus of claim 13wherein each spacer includes a plurality of grip elements extending intoat least one resilient member.
 15. The drilling apparatus of claim 14wherein at least some of the resilient members include recesses thatreceive at least some of the grip elements of a t spacer.
 16. Thedrilling apparatus of claim 13 wherein at least some spacers include afirst plurality of grip elements extending in a first direction into afirst adjacent resilient member and include a second plurality of gripelements extending in a second direction into a second adjacentresilient member.
 17. The drilling apparatus of claim 12 furthercomprising a plurality of impact attenuating stacks disposed generallyparallel to one another in the chamber, each impact attenuating stackcomprising: a plurality of resilient members disposed along an elongateguide member, each resilient member including an alignment aperture andreceiving the guide member therethrough.
 18. The drilling apparatus ofclaim 13 wherein each impact attenuating stack further comprises: afirst end member; and a second end member spaced a distance D from thefirst end member and including an alignment aperture therethrough;wherein the guide member is attached to the first end member and isslidingly received through the alignment aperture in the second endmember.
 19. The drilling apparatus of claim 12 wherein the alignmentaperture of each resilient member includes a plurality ofradially-inward protrusions circumferentially surrounding the guidemember.
 20. An impact attenuating device comprising: a longitudinalaxis; an elongate housing comprising first and second housing endsspaced-apart along the axis, an internal chamber, and a housing baseaxially spaced from the first housing end; and an impact attenuatingmedia assembly in the housing, the media assembly comprising: areceiver; an attenuator base axially spaced-apart from the receiver andhaving an alignment hole; at least a first stack of impact attenuatingmedia disposed between the receiver and the attenuator base, the stackcomprising a plurality of resilient members; and a guide memberextending from the receiver to the attenuator base, through the stack.21. The impact attenuating device of claim 20 wherein the housing baseincludes an alignment hole; wherein the guide member includes first andsecond guide member ends, the first guide member end fixedly coupled tothe receiver; wherein the alignment holes of the attenuator base and thehousing base slidingly receive the second end of the guide member;wherein the device further comprises a fastener coupled to the guidemember second end, the fastener configured to allow the guide membersecond end to move away from the attenuator base in a first axialdirection and configured to inhibit the guide member second end frommoving away from the attenuator base in a second axial direction. 22.The drilling apparatus of claim 21 further comprising a containment tubeextending along the axis and including an open end coupled at thehousing base and a closed end axially spaced-apart from the open end,the containment tube configured to receive the guide member when itextends through alignment hole of the housing base.
 23. The drillingapparatus of claim 20 wherein each resilient member comprises analignment aperture that slidingly receives the guide member, wherein thealignment aperture includes a plurality of radially-inward protrusionscircumferentially surrounding the guide member.
 24. The drillingapparatus of claim 23 wherein the alignment aperture of each resilientmember further includes a plurality of spaces between adjacentprotrusions; and wherein the volume of each space is substantially equalto the volume of each protrusion.
 25. The drilling apparatus of claim 20wherein the media assembly further comprises a plurality ofradially-extending stabilizers, wherein the stabilizers are slidinglyreceived along the inner surface of housing body.
 26. The drillingapparatus of claim 20 wherein the stack of impact attenuating mediafurther comprises a plurality of spacers, each spacer including analignment aperture receiving the guide member therethrough; wherein atleast some spacers include a first plurality of grip elements extendingaxially in a first direction into a first adjacent resilient member andinclude a second plurality of grip elements extending axially in asecond direction into a second adjacent resilient member.
 27. Thedrilling apparatus of claim 26 wherein at least some of the resilientmembers include recesses that receive at least some of the grip elementsof a spacer.